For a charcoal grill:Grill mushroom caps (top side up), eggplant slices, red onion slices and pepper pieces on the greased rack of an uncovered grill directly over medium coals for 8 to 10 minutes or just until tender and lightly browned, turning halfway through grilling and topping inside of mushroom caps with 3/4 cup of the cheese for the last 2 minutes of grilling. (For a gas grill: Preheat grill. Reduce heat to medium. Place mushroom caps, eggplant slices and red onion slices on greased grill rack over heat. Cover and grill as above, topping inside of mushroom caps with cheese as directed.)